PECVD is often a method of choice for depositing various layers of material in semiconductor processing. In a typical PECVD reactor, one or more volatile precursors are introduced into the process chamber, which is typically maintained under vacuum. After the plasma is ignited within the chamber, the precursors react to deposit a layer of material on a substrate. A variety of layers used in integrated circuit (IC) fabrication can be deposited by PECVD, including inter-layer dielectrics (ILDs), diffusion barrier layers, etch stop layers and various hardmasks. For example, silicon carbide (SiC), silicon nitride (SiN), and carbon (C) layers are often deposited by PECVD.
PECVD-deposited carbon layers have been commonly used as ashable hardmasks (AHMs) in integrated circuit fabrication, where they are employed during patterning of underlying dielectric layers. After the patterning of dielectric is completed, the carbon hardmask is typically removed by ashing.
Conventional PECVD-deposited carbon AHMs usually contain significant amount of hydrogen (H) in addition to carbon, are typically rich in sp3 carbon, and are substantially non-conductive.